MELBOURNE (AP) _ National Australia Bank Ltd. said Monday it will pay $1.23 billion to buy HomeSide Inc., one of the largest full service residential mortgage banking companies in the United States.

Don Argus, chief executive officer of NAB, which is one of Australia's four major banks, said the acquisition is another step in NAB's strategy to build a global banking and financial services organization.

HomeSide's four major shareholders, which account for 76 percent of its issued stock, have agreed to the proposed acquisition and will vote in favor of the deal at a meeting of shareholders, NAB said. The acquisition, which is also subject to regulatory approval, is expected to be completed in the first quarter of 1998.

HomeSide had net income of $20.1 million for the three months to Aug. 31, up from $18.1 million in the fiscal first quarter.

The U.S. residential mortgage company has a customer base of more than 1 million homeowners throughout the United States.

The purchase price is equivalent to $27.825 for each HomeSide share. HomeSide's stock closed at $24.25 on the New York Stock Exchange Friday.

HomeSide has about $97 billion of loans in its servicing portfolio.